Known prior art safety belt buckle constructions which typically includes a stamped open frame with channel sides limiting pivotal latch deflection under load include the following U.S. Pat. Nos. 3,131,451; 3,237,256; 3,242,546; 3,274,655; 3,277,548; 3,449,800; 3,465,393; 3,483,599; 3,588,969; 3,623,191; 3,639,951; 3,686,720; 3,716,895; 4,015,094; 4,052,775; 4,060,879; 4,064,603.
Under heavy test loading it has been found that the channels of such typical safety belt buckle frames formed as sheet metal stampings provide limited resistance for retaining the latched tongue against deflection incident to the angularity between the latch pivotal engagement with the reaction surface of the frame and the latch engagement with the apertured tongue of the connector. Another critical area of limited strength in the prior art stamped frames is the reaction surface for the latch normally formed with a right angle bend at the end of the frame which is engaged by the base of the latch. In each case heavy loading on the belt subjects the stamped channels and reaction base of the frame to critical bending loads inherently incident to the unsupported extremities of the stamping channel and angle edges.